Water purification



Feb. 23, 1943. c. G. HAWVLEY 2,311,830

WATER PURIFICATION Filed March 16, 1939 11 Sheets-Sheet 1 r I v N- INVENTOR. QcHARLEs & HAWLEY ATTORNEY.

Feb. 23, 1943. c. G. HAWLEY WATER PURIFICATION Filed March 16, 1939 ll Sheets-Sheet 3 I INVENTOR. CHARLES 6. HAWLY BY uumlmmmnmmmlg ii llllllll lllllllllillllfiil llllllllllllllllllllllmllllfl IIIIHIIIIIIIIIIYINTIII \llllllllllllllllllllllllll 1 .IIIIIIIIIIIIIII lllllll ATTORNEY.

Feb 23, 1943, C36. HAWLEY ,311,

' WATER PURIFICATION Fi led March 16, 1939 ll Sheets-Sheet 4 FIG. I 5

' INVENTOR. CHARLES e. HAWLEY BY DW ATTORNEY.

Feb. 23, 1943. c. s. HAWLEY 2,311,830

WATER PURIFICATION Filed March 16, 1959 ll Sheets-Sheet 5 INVENTOR. CHARLES s. HAWLEY BY 1 I h. x M .v

l ATTORNEY.

Feb; 23, 1943. c. HAWLEY 2,311,830

WATER PURIFICATION Filed March 16, 1939 11 Sheets-Sheet 6 Feb. 23, 1943.

c. G. HAWLEY 2,311,830

WATER PURIFICATION Filed Maw 16, 1939 11 Sheets-Sheet 7 CHAMES G. HAWLEY I Feb, 23,- 1943. c, H WLEY I 2,311,830

WATER PURIFICATION v Filed March 16, 1939 11 Shets-Shet 9 ATTORNEY.

Feb 23, 1943. c. G.QHAW-LEY 2,311,830

WATER PURIFICATION Filed March 16, 1939 l1 Sheets-Sheet 10 v INVENTOR. I CHARLES HAWLGY ATTORNEY Feb.- 23, 1943. c. G. HAWLEY 2,311,830

WATER PURIFICATION Filed March 16, 1939 11 Shets-Sheet 11 FIG.3|I

INVENTOK CHARLES 6. HAW LEY BY & h

ATTORNEY.

Patented Feb. 2;,"1943 UNITED STATES-PATENT OFFICE WATER PURIFICATION Hayley Degenhardt Hawiey, execntrices of Charles Gilbert Hawley,

d llawley 2 Claims.

The invention relates to the purification of municipal and industrial waters. Two phases are to be considered. The first has to do with the preparation of water for domestic use: the second, .with the purification or rectification of water after it has become sewage and before it can be safely returned to any source of domestic water. The present invention suits both purposes. Procedures are the same and the apparatus here provided serves one purpose as well as the other. g

The primary object of this invention is to forcibly impose purity upon flowing water by mechanical operations thereon, and, to avoid the variables of, and dependence upon, the slow processes of nature. A further object of the invention is to provide sewage treatment apparatus in a readily transportable and installable form of such low cost as to encourage a general improvement in public waters. Still other objects of the invention will appear hereinafter.

Virginia Taylor eceased, assignors, by mesne assignments, to

Corporation, Cleveland, Ohio, a corp ration 01 Ohio Application March is, 1939, Serial No. 262,141

on. ua-s).

lineH of Fig. 2; Fig.

associated filter or screen; Fig. is a plan view taken from Fig. 9; Fig. 11 is a sectional view on In contrast with the extended purification" processes of the past, the present invention takes the form of an abbreviated unitary machine which in lieu of permissive natural actions imposes radical conditions that expedite and ensure the prompt purification of the water, thus enabling the work to be done within a minimum of time, space and cost.

As will appear, mechanical filtration here conditions the polluted water for immediate completion. Next, the polluted water is finely subdivided in the presence of abundant air and is thus charged with oxygen to an extent which ensures ultimate stability and precludes subsequent the line ii--ll of Fig. 9; Fig. 12 is a horizontal section on the line 12-12 of Fig. 10; Fig. 13 is a vertical section on the line 13-43 of Fig. 11; Fig. 14 is a sectional view of the aeration unit or component of the machine; Fig. 15 is a sectional view on the line l5i5 of Fig. 14; Fig. 16 is a sectional view on the line i6-i6 of Fig. 14; Fig. 1'7 is an enlargedsectional detail illustrating the functioning of annexation unit; Fig. 18 is a sectional view on the line 18-48 of Fig. 1'7; Fig. 19 is a sectional view on the line l9l9 of Fig. 1'7; Fig. 20 is a sectional view on the line 20-20 of Fig. 1'7 Fig. 21 is a sectional elevation of the sedimentation tank; Fig. 22 is a plan view thereof; Fig. 23 is a sectional detail of the tank end; Fig. 24 is a sectional end elevation of the tank on the line 2|24 of Fig. 21; Fig. 25 is a sectional view on the line 25-25 of Fig. 21; Fig. 26 is like unto Fig. 1 but shows the components or units-closely assembled or associated; Fig. 27 is a plan view putrefaction. -A contact period and sedimentaitself to simplification, and at low cost admits of a degree of perfection not hitherto attainable except at high cost. The machine as a whole and as here presented comprises a sequence of standardized metal units adapted to quantity production and readily arrangeable in the order andnumber'needed to afiord requisite capacities and end results.

The invention will be readily understood upon reference to the accompanying drawings, in

which Fig. 1 is a diagrammatic sectional eleva-.

tion of a water purification system embodying the present invention; Fig. 2 is a plan view thereof; Fig. 3 is an end elevation taken from taken from Fig; 26; Fig. 28 illustrates the invention in multiple form; Fig. 29 illustrates a modifled arrangement of multiple units; Fig. 30 is still another arrangement thereof; and Figs. 31, 32, 33 and 34 illustrate special applications of the invention suited to different purposes.

The invention here presented is adapted for embodiment upon any scale and in any size which may be required and may be used as a substitute for and to supplement existing water purification systems; indeed, its general applicability and scope are to be understood as applying to the most extensive operations.

But on the other hand it is to be understood that the special purpose of the present invention is to simplify procedures and reduce costs of water purification to an extent which will enable even the poorer communities and industries to safeguard themselves and neighbors.

With that special object in view, Figs. 1 and 2 and Figs. 26 and 2'7 illustrate the invention as a typical sewage disposal unit suited to a town of approximately 1,000 population. The revolutionary character of the invention will be recognized in its small size and obvious low cost, particuthe line larly when it is further understood that the plant illustrated is less than fifty feet long, only six feet in depth, affords a detention period of not over one hour and yet accomplishes an almost perfect purification of domestic sewage at the rate of approximately one hundred thousand gallons per day.

Such a simple and yet complete unitary apparatus comprises a sequence of self-contained, all metal components or parts, each performing a definite function and each dependent upon another, as will be explained. By preference, all components are arranged upon a, single level or foundation I. The sewage enters the system from the influent channel 2, and, flowing from end to end under a slight hydraulic head, departs through an outfall 3.

The component parts will be best understood if separately explained, for each has a definite function to perform, each in relation to succeeding parts.

The trash trap A shallow metal trough 4, elevated above the level i, receives the sewage from theinfluent 2. The liquid leaves the trap through an elevated weir 5, beyond an extensive opening 6 in the side of the trough. An overflow I, leading from the upper part of the trough controls the liquid level 8 therein.

The capacity of the trough is small, the purpose being to maintain turbulance and yet allow grit to settle to the bottom of the trough, for later disposal along with floating trash which may be caught in the trap. Such trash is entrapped by a bar screen 9 which occupies the opening 6. That screen is of peculiar construction. It comprises a number of parallel rods or tines 9' which hang from a cross bar 9", attached to the side of the trough above the level 8. The tines 9' are of less depth than the trough, terminating well short of the bottom of the trough; in other words, the lower ends of the bars 9' open directly into the lower part of the trough. Such a bar screen is kept substantially clear by the sweep of the sewage across it and by the manual manipulation of a comb or brush in the hands of a workman. The trash is left in the trap, to be scraped out over the inclined end 4' thereof. The bar screen is readily removable as a whole, being swung upon pivots, at the top. It stands inward from the side of the trap, to facilitate cleaning. (See Figs.

The filter or screen A screen pocket [0 is applied to the opening 6 in the side of th trash trap 4, and the liquid having passed through the bar screen 9, flows out over the weir 5, and there immediately encounters a much finer screen i i, which latter, functions to abstract all matters which might clog or block subsequent operations of the system.

. The screen is of cylindrical form, with a central shaft l2, and is slowly rotated upon a horizontal axis, as by a suitably geared motor l3.

The screen is of peculiarly simple construction, comprising a skeleton-like cage formed by end rings i4 and i5 and cross bars i6 and a wrapping of wire. The wire is spirally wound upon the cage and the wraps of wire are close together. In practice, a wire of diameter is used and the spacing between wraps is still smaller, affording an extremely flne screen surface, interrupted only by the infrequent cross bars l6.

As well illustrated in Figs. 9 to 13, the top of the screen rises above the trough level 8 and above the weir 5. The weir 5 is formed by a flexible flap or extension 5' on the screen pocket and is normally pressed against the smooth wire face of the screen by the weight of the water in the trough. The flap 5' extends from end to end of the cylindrical screen and leakage is negligible. So-called cheek plates I! are extensions ofthe sides of the opening 6, and ride in slots I8 provided therefor in the end rings, preventing leakage over the ends of the. screen.

The screen rises behind the flap 5' in the direction of the arrow IS in Fig. 11, and the rotation of the screen obviously serves to lift screenings from and over the liquid surface 8 which is maintained in the trough 4.

Falling through the top of the screen, the liquid escapes through the bottom of the screen. washing the wire at that point. It will be noted that the liquid level 20 which is maintained in the screen pocket, is below the bottom of the screen and that the wire is constantly washed by the falling water.

Obviously, the matters which are caught upon the wire face of the screen are slowly carried across the top of the screen, draining thereon and for delivery upon the opposite side of the screen. Such delivery is rendered positive and the screen is finally cleaned by a blast of air direct-ed outward from the interior of the screen.

One end of the screen is open (see Figs. 9 to 13) and a fixed nozzle 2|, served by a motor driven fan 22 and coacting with a parting strip 23 directs a sharp blast of air through the wire face I of the screen, effectively cleaning the same.

Thus formed and equipped, the screen functions continuously without clogging and without care. And, a screen rotation of two to four revolutions per minute is amply fast to take care of the heaviest sewage.

Referring now to the left hand end of Figs. 1 and 11, it will be noted that a deep furnace stack 24 rises adjacent the screen and presents a fuel and air throat 25 directly opposite the screen blast nozzle 2|. An ignition fire is maintained in the lower part of the stack and the high temperature therein serves to evaporate the small quantity of water which accompanies the screenings blown from the screen. The screenings are well drained upon the exposed top of the screen, leaving a minimum of moisture for evaporation in the furnace.

The moisture leaves the furnace stack in the form of steam while the dried solids burn in suspension in the lower part of the furnace stack, the operation continuing automatically as long as an ignition temperature is maintained in the lower part of the furnace.

By preferance, the cross sectional area of the throat 25 is closely limited to avoid an excess of air. Suitable air feeding openings are provided in the lower part of the furnace and the regulalation of the combustion described is easily accomplished. The practical use of this feature of the invention is made clear by the fact that sewage screenings have a value of 5,000 to 9,000 B. t. u.s per dry pound and burn readily in suspension.

The sewage solids having been disposed of, the final purification of the liquid is undertaken.

That purification involves the eradication of dissolved solids and colloidal matters and is here accomplished by direct oxidation; in other words, by forcibly impregnating the sewage with air. Impregnation may be substantially instantaneous as provided for in Figs. 31 and 32 or may be of a protracted nature, as shown in Figs? 1 and 2,

depending upon the degree of purity demanded in the aflluent of the system. A small expenditure of power is involved iii the process and the degree of purity attained is measured by the power input, becoming a known effect and quantity.

As about to be described, the aeration process of this invention is practiced by finely subdividing the sewage in air; and, is performed by lifting the liquid from the surface of the moving stream. A cyclonic action is here employed, taking ad vantage of the surface tensions of air and water and involving the smallest expenditure of power.

Whether aeration be instantaneous or protracted depends upon the duration of the exposure of the liquid to air. The cyclonic action about to be described is so effective as to accomplish an almost perfect instantaneous impregnation of the sewage with air and the process is thus practiced to advantage; but on the other hand, superior advantages are to be gained by ganic matters. These concurrently sequential operations effectively stabilize the sewage; and

' comprise the gist of the present invention.

the protraction of aeration and is here accomplished by a circulatory action of the liquid.

Cyclonic aeration This invention has to do with liquids which tend to putrefy, a designation which includes sewage and like organically polluted waters not containing or supplied with enough oxygen. to prevent putrefaction.

Filtration and sedimentation may be relied upon to palpably purify organically polluted water but much more is required if water is to be actually reduced to a state of purity. This invention is based upon'the conception that final purification can be brought about only through oxidation; in other words, by admixture with air, and the object of the invention is to accomplish a desired degree of oxidation at low cost. Such oxidation may be imposed at any time after the sewage passes the described screen.

The discovery now to be reported is, that while the solubility of oxygen in water is ordinarily regarded as limited to a few parts per million, varying with temperature, it is in fact possible by operations about to be described, to imprison in I even very foul water enough air to provide in advance for the firm stabilization thereof and thus afiord ample time and means for the chemical and/or the bio-chemical destructive reduction of contained organic matters; thereby protecting any diluting water with which such aerated sewage is admixed; and if desired, even increasing its oxygen content. A great range of aeration is here provided at low cost and whether or not the process shall be carried through to completeness may be freely determined to accord with local sanitary conditions and economic circumstances.

A further discovery hereof is that by a brief atomization of sewage and the use of air in swift motion, it is possible to displace and blow out of sewage quantities of dissolved, imprisoned or entrained gases, vapors, and light organic structures; which, if allowed to remain would militate against prompt and healthful disposal of the main load of organic matters. Next, by abruptly terminating such atomization (restoring the liquid to mass formation) it is possible to I charge the purged or air-scrubbed sewage with air in relatively large volume and in the state of minute particles or globules which the massed water thereafter holds in relatively firm imprisonment, suspension or solution, and hence readyfor combination with therein adjacent or- Speaking further of the present invention, it

may be said to comprise or include the purging and enforced aeration of sewage and the like; and, in contrast with former methods of aerating water en masse, it consists in performing the operations in space and in a state of fine atomization or pulverization within a restricted passage, immediately followed by a consolidation of the liquid. These effects are here attained by the cyclonic operation of swiftly moving air upon the polluted water, comprehending and employing these discoveries in specially invented cyclonic apparatus, all as'made clear by Figs. 11 to 20.

However it may arrive at that point, the liquid to be treated has been screened and is supplied or maintained at a level 26, where it.is exposed to the open atmosphere. The liquid is lifted from that surface by the force of swiftly whirling air which serves to disintegrate the liquid and expose every part thereof to contact with the air.

The means here provided for the elevation of the liquid comprise a plurality of fixed centrifugal tuyeres 21, each having many intake tuyere openings and all served by a suction box 28 which is common thereto. As shown, the suction box is supported above the liquid surface 26,

and the bottoms of the tuyeres are submerged in the liquid, allowing the liquid to enter freely through the tuyere openings.

The tuyeres serve as avenues through which liquid is drawn from the surface 26 and delivered within the box 28. As shown, the suction box is exhausted by a suction fan 29, of which 3d is the exhaust stack. A suction of three inches (of water) here affords an air velocity approximating six thousand feed per minute and proves adequate to break up the water and lift it a much greater distance. I

Obviously, the air is drawn through the tuyeres at this high velocity but loses velocity within the capacious suction box, allowing the elevated water to sink or settle to the floor 28a of the box. The parts 28' and 28" are collecting surfaces and bailies which intercept particles of water that might otherwise be drawn into the fan.

The water which is thus elevated and transferred from the liquid surface 26 to the interior of the suction box may be returned to the surface 26 in a circulatory manner as depicted in Figs-Land 2 and elsewhere, or may be collected and moved forward in the stream. as shown in Figs. 31, 32 and 33, to which later the surface 26 into many small streams or films and then to finely disintegrate the liquid within the passing volume of air.

The tuyere 21 is made of metal. It is of cylindrical form, with a closed bottom 3| and an open top 32. The cylindrical wall is sheared and pressed to form a large number of elongated tangential blades 33, which forma like number of tangential intake tuyere openings 34, all having the same direction.

The tangential blades extend from the bottom 3| nearly to the top 32, leaving a blank section 35 above the blades. That section of the tuyere rises through and is fastened in the bottom 23a of the suction box 28. During operation, the air and the liquid enter the tuyere simultaneously. Being directed by the tangential tuyere blades, the air takes on a swift whirling motion within the tuyere and, as a result of such motion, the accompanying liquid is quickly disintegrated and, yielding to the centrifugal forces developed, the disintegrated liquid is spirally whirled upward and expelled through the open serving the energy required to whirl the pul-.

verized liquid and elevate it within the tuyre.

The operation of the tuyere is clearly depicted by Figs, 17 to 20. Fig. 20 illustrates the admission of liquid to the base or bottom of the tuyre. Fig. 19 depicts the whirling disintegrated liquid intermediate the height of the tuyere, showing how the whirling liquid is kept or maintained in and across the path of the entering air. Fig. 18 shows how the liquid having been raised to a point above the tops of the tuyere openings is centrifugally compacted and collected against the imperforate top or neck of the tuyere. Fig. 17 shows how the disintegrated liquid is centrifugally expelled from the top of the tuyre.

The dimension 36 appearing in Fig. 17 represents the pressure drop between the surface 26 and the interior of the suction box. Assuming that difference to be three inches as before mentioned, it will now be apparent that the liquid is elevated not only to the extent necessary to lift it through the higher tuyre but also to a considerable distance into the suction box.

As a result of the disintegration of the liquid within the closely confined whirling stream of air, a high ratio of oxygen is communicated to the water. It is particularly to be noted that the conglomeration of air and liquid particles which takes place within the tuyere is consoli dated by the centrifugal collection of the liquid within the imperforate neck portion of the tuyre, just prior to the centrifugal discharge of the liquid from the tuyere. In consequence. the liquid is found to be charged with a quantity of oxygen which is sumcient to freshen and stabilize even stale sewage.

It isnow to be noted that the described disintegration of the polluted water in air, appears to explain the pronounced extermination of protozoa, and anaerobic and facultative bacteria, as observed in this operation. Apparently the presence of ample oxygen and the swift change from tensional imprisonment within the water, to sudden freedom upon the surfaces of the water particles, has the eifect'of bursting or destroying the fragile cells of protozoa, and pathogenic bacteria. The more minute aerobic bacteria in considerable measure escape destruction and may be discharged with the aerated water, thereafter to play their proper part in water purification.

As before stated, the aeration of the liquid 'may be momentary or may be protracted. By

preference. it is protracted as and in the manner shown in Figs. 1 and 2. To that end, the screened sewage, through a duct 31, is delivered to the lower part of a tank or container 38, the volumetric capacity of which ensures retention of the sewage, for a measurable time.

The flow is continuous, the liquid leaving the upper part of the tank 38 through an outfall duct'38. As will be understood, the suction fan 29 is in continuous operation and the indraft of air through the tuyeres 21 takes place continuously. In this case the liquid from the floor 28a of the suction box returns directly to the tank 38 through the capacious standpipe 40.

'Thus the liquid from the tank 88 is repeatedly elevated and aerated for as long a time as the liquid remains in the tank 38. Such detention may be several minutes in duration and during that time an abundance of oxygen is disseminated in the liquid, ensuring the freshness and stability of the sewage.

The circulation of the water coupled with the inflow through the duct 31 serves to keep all sewage solids in a state-of suspension and a chief result of the aeration described is to charge not only the water but also the sewage solids with particles of oxygen, with consequent assurance of the reduction of those solids by oxidation.

When the screened sewage has been thus forcibly impregnated with air, it is in safe condition for dilution, for it then contains enough oxygen to prevent subsequent putrefaction of organic matters, with little if any dependence upon the oxygen content of the diluting water.

Preference has been expressed for the protracted aeration of the sewage, but on the other hand it is to be understood that the invention is not limited thereto for, as a matter of fact, the cyclonic aeration here described is so eflicient that the mere single passage of the liquid through the described centrifugal tuyeres is sufficient to stabilize sewage.

In contrast with the circulatory aeration above described, Fig. 31 illustrates the invention as practiced in a continuous manner. The sewage from the screen H is conducted to the aerating tuyeres 21 through a trough-like channel 4|. The liquid is elevated from the trough 4| and falling within the box 28, escapes through an outfall duct 43. Although aeration is here limited to a single pass or transfer of the liquid it is adequate to stabilize the sewage.

In the structure of Fig. 32 the supply channel 44 is combined with a settling pocket 45. The latter affords time for a precipitation of sewage solids below the aerating tuyres 21 prior to discharge through the outfall 43. Matters which are precipitated in the pocket 45 are discharged through a pipe 46, leading from the bottom thereof and are returned to the screen I l, as will be explained.

It is desirable that the tuyere openings 34 (see Figs. 17 to 20) shall be narrow and shall thus limit the liquid to streams which are in the nature of films and therefore easily disintegrated by the air whirling through the tuyeres. The

, settling pocket 45 is a precaution against screen failure. Coarse matters which might clog the tuyeres 34, are settled out in the pocket 45 and are returned for removal by the screen.

Figs. 33 and 34 respectively represent momentary and protracted aeration methods. The tank 41 (Fig. 33) is employed as a means of distributing the sewage to the many tuyeres 21. The latter are of the single-pass arrangement, the aerto end of the tank.

Detention here has two purposes, the first being an allowance of a contact period, during which the oxygen received-from the air actsupon the organic matters in the sewage. The second purpose of detention is to allow time for the gravitational separation of the various sewage solids and scums. Matters heavier than water slowly sink to the bottom of the tank. Those which are lighter rise to the surface. Means are here provided for the removal of both settled sludge and floating scum. In practice, a detention of one hour has proven to be adequate for all purposes.

The unitary tank 48 hereof is of novel design I and utility andconstitutes a new article of manufacture in that it is a self-contained, all metal,

and readily transportable unitary part of this sewage treating machine, and like otherparts of this machine is adapted to factory production,

' not limited to construction in the field. It is to' be remembered always that the underlying purpose of this invention is to reduce costs and hence this machine as a. whole is designed to be produced by methods of highest efficiency and to be of such simplicity that it can be successfully used by the men commonly available for such work, no special skill being required for regulation or control. I

As well shown by Figs. 5 to 8 and by Figs. 21

' to 25, the metal tank of this invention is an elongated thin. walled-trough of V-shape cross section, the bottom being formed to facilitate the collection and discharge of sludge. The length of the tank may be ten times its width and, most conveniently, the tank is made or a number of bent plate sections which are united by means of end flanges 49. Each end of the tank comprises a plate 50, which is bolted to the end flanges (see Fig. 23). Rigidity is afforded by top flanges 5| and those flanges may be Joined by cross ties.

Stability is. afiorded by the rectangular shapes 0f the ends 5|] and the tank is additionally supported by intermediate cradles 52 (see Fig. 7) Entering through a distributing duct 53, the screened and aerated sewage progresses slowly toward the end weir 54 and the outfall 3. Sedimentation and levitation occur during the slow movement of the liquid.

i It is ofparticular moment that the described aeration of the sewage is a thorough going operation which has the effect of disengaging soapy matters, grease and oil, ensuring the accumulation thereof upon the surface of the slowly moving stream. In that way the most diilicult sewage matters are presented for disposition.

Various devicesmay be employed for the discharge of the floating scum. The simplest means comprises a cross baille .55 combined with a trough 55', and, means by which the level of the liquid in the tank may be raised at will, so that levels.-

the scum may pass. into the cross trough. By

preference, two baflles and cross troughs are used,

adjacent the tank.

, Sludges which settle in the V-bottom of the tank are moved endwise therein by an underwater current which is here created for that purpose. A pipe 59 positioned in the; lower part of the tank is supplied with water under slight pressure, as through a connection 80. By pref; erence, the pipe is of the V-shaped cross section shown in Fig. 25 and spaced nozzles 6!, leading from'the interior of the pipe extend downward and backward to direct streams of water against the bottom of the tank. The flow of water from the nozzles is gentle but, being all in one direction, is sufficient to move the sludge particles to the opposite end of the tank. Accumulating at that point, the sludge is discharged through an hydrostatic pipe 62 and it is to be-noted that the sludge pipe 62, through the medium of a small pump 63, delivers the sludge to the fine screen H. It will now be evident that the settled sludge which isrecovered in the sedimentation tank is returned to the trash trap and screen. The excess of water is disposed of through the screen and the sludge particles in greater part are intercepted by the screen and are thereby delivered directly to the combustion furnacev 24.

Where two or more sludge return pipes (see 46 and 62 of Fig. 32') are employed, a pump sump 64 receives the direct flows of sludge, the pump 63 exhausting'the sump and controlling tank Figs. 1 and 2 by the addition of a second aerator 28a: make provision for a terminal aeration of theeilluent from the sedimentation tank 68, a measure of importance when *a final stage of purification is required.

It is notable that the tuyeres illustrated are of a length or height that exceeds the air pressure difference (36) between the bladed exterior and the top of thetuyre. Yet a large volume of liquid is made to rise through the .tuyere. This is explained by the fact that the superficial area, the sail area, of thev liquid is here tremendously increased and the polluted water is easily swept upward by the moving air. in turn this explains v the small consumption of power.

Another noticeable fact concerning this process,

isfthis: The collodial matters contained by sewage are observed to be, in considerable measure,

tuyeres hereof, particularly those of small diameter.

The importance of the present invention is well illustrated or explained by the results thus far obtained. Raw sewage, merely screened, has been operated upon as herein described and, though carrying a heavy burdenof putrescible matter, .has remained stable for a period much longer than ever before reported; and most remarkable when itis realized that such stability was imparted in so brief a time'of passage, little if any .more than one second. The same sewage, when It is to be noted that the whole process is conducted in open air and attatmospheric temperature.

ratus may be employed in arts other than the treatment of sewage, it is herein claimed as a structure capable of such other uses.

In the foregoing discussion of the treatment of sewage, emphasis has been laid upon the importance of the oxygen which is derivable from Because the herein described stabillzingappaair. The nitrogen of air has been virtually disregarded because its part in the chemistry involved is not well defined. Nevertheless, it may be found to play an important part in the stabilization of sewage, either at the instant of application, or at a later time.

Having thus described my invention, I claim as new and desire to secure by Letters Patent:

1. Apparatus for the treatment of organically polluted liquid comprising, in combination, a screen pocket provided with an inlet for polluted liquid and with an outlet, a screen controlling the outlet from said pocket, a treating chamber in communication with the outlet from said pocket and adapted to receive screened liquid therefrom, said treating chamber being provided with an outlet arranged to establish a liquid'level in said chamber, a suction box positioned above said treating chamber,-means to exhaust said suction box, a fixed centrifugal tuyre extending from below the liquid level established in said treating chamber for discharge into said suction box and a conduit extending from said suction box to a point in said treating chamber below the liquid level established therein.

2. Apparatus for the treatment of organically polluted liquid comprising, in combination, a

screen pocket provided with an inlet for the reception of polluted liquid and with an outlet, a rotary screen positionedto control said outlet and arranged to elevate screenings. above the level of the stream from said outlet, a furnace,'a stack for said furnace, means for removing screenings from said screen at a point remote from the stream from the outlet of said screen pocket and a conduit arranged to lead from adjacent the point of removal of screenings-from said screen to said furnace and adapted to receive the screenings as they are removed fromsaid screen and afford a passage therefor to said furnace.

, CHARLES GILBERT HAWLEY. 

